Fuel cell system and hydrogen leak decision method in fuel cell system

Abstract

A fuel cell system includes: a fuel cell; a hydrogen tank; a hydrogen supply flow path configured to connect the hydrogen tank and the fuel cell to each other; a valve element configured to, when closed, shut off supply of hydrogen from the hydrogen tank to the hydrogen supply flow path; a pressure sensor; a pressure reducer configured to reduce internal pressure of the hydrogen supply flow path; and a controller configured to decide presence or absence of a hydrogen leak in the fuel cell system upon a power-generation halt of the fuel cell. The controller: while closing the valve element, reduces the internal pressure of the hydrogen supply flow path to a first pressure value by the pressure reducer; after the pressure reduction to the first pressure value, decides presence or absence of a suspicion of a hydrogen leak by using a variation of a pressure value acquired from the pressure sensor; when deciding a suspicion of a hydrogen leak is presence, reduces the internal pressure of the hydrogen supply flow path to a second pressure value lower than the first pressure value by the pressure reducer; and after the pressure reduction to the second pressure value, decides the presence or absence of a hydrogen leak by using a variation of a pressure value acquired from the pressure sensor.